Rear Differential

Complete removal and replacement of the rear differential assembly on a 2007 Ram 3500 4WD with 5.9L Cummins diesel engine, including driveshaft disconnection, axle separation, and fluid refill.

Warnings

Tools required

Parts

• Differential cover gasket × 1 — Use OEM specification or RTV silicone gasket maker
• Rear driveshaft U-joint strap bolts × 4 — Use OEM specification
• Differential mounting hardware (inspect and replace as needed) × 1 — Use OEM specification

Fluids

• 75W-90 synthetic gear oil — 5.5 qt

Preparation

1. Park vehicle on level ground and set parking brake firmly
2. Place wheel chocks in front of front wheels
3. Loosen rear wheel lug nuts while vehicle is on ground
4. Raise rear of vehicle with floor jack and support securely on jack stands rated for vehicle weight under frame rails
5. Remove rear wheels completely
6. Allow differential to cool if vehicle was recently driven
7. Clean area around differential cover, driveshaft connections, and mounting points
8. Apply penetrating oil to all fasteners to be removed and allow to soak

Procedure

1. 1

   Drain differential fluid
   Place drain pan under differential. Remove the differential cover bolts in a crisscross pattern, starting from the top and loosening bottom bolts last. Carefully pry the cover away from the housing at the bottom edge to allow fluid to drain. Once drained, remove cover completely. Inspect drained fluid for metal shavings or debris indicating internal damage.
2. 2

   Mark and disconnect rear driveshaft
   Using a paint pen or marking tool, mark the relationship between the rear driveshaft flange and the differential pinion flange for proper alignment during reassembly. Remove the U-joint strap or flange bolts at the differential end (verify count and connection type against the actual AAM 11.5 axle configuration). Support the driveshaft and carefully separate it from the pinion flange. Wire or strap the driveshaft to the exhaust or frame to keep it out of the way. Do not allow the driveshaft to hang freely as this can damage the slip yoke or center bearing.
3. 3

   Disconnect brake components
   If equipped with rear disc brakes, disconnect the parking brake cables from the calipers by removing the cable clips and unhooking the cables. For drum brakes, disconnect parking brake cables at the backing plates. Remove any brake line brackets attached to the differential housing or axle tubes that would interfere with removal. Do not disconnect hydraulic brake lines unless absolutely necessary.
4. 4

   Disconnect ABS wheel speed sensors
   Locate the ABS wheel speed sensor connectors on each side of the rear axle. Disconnect the electrical connectors and remove any clips or brackets securing the wiring to the axle housing. Carefully route wiring away from the differential to prevent damage during removal.
5. 5

   Support differential with transmission jack
   Position a transmission jack or heavy-duty floor jack with a differential adapter under the center of the differential housing. Raise the jack until it just contacts the differential and secure it with a chain or strap. The differential should be stable on the jack but not supporting full weight yet.
6. 6

   Remove shock absorber lower mounts
   Remove the lower shock absorber mounting bolts on both sides. This may require supporting the axle to relieve tension. Push shocks up and out of the way, securing them to the frame if necessary.
7. 7

   Disconnect track bar and sway bar links
   If equipped, disconnect the track bar from the axle bracket by removing the mounting bolt. Remove sway bar end link bolts from their axle mounting points. Allow these components to hang freely or support them to prevent stress on bushings.
8. 8

   Remove leaf spring U-bolts
   Remove the U-bolt nuts on both sides of the differential. There are typically two U-bolts per side securing the axle to the leaf spring. Keep track of all spacer plates and hardware for reinstallation in the correct order. Once U-bolts are removed, the differential will be supported only by the jack.
9. 9

   Lower and remove differential assembly
   With the differential secured to the jack, slowly lower the jack while carefully guiding the assembly. Watch for any remaining brake lines, wiring, or vent hoses that may still be connected. Maneuver the differential assembly out from under the vehicle, being careful of the long axle tubes and limited clearance. You may need to angle the assembly to clear suspension components.
10. 10

    Prepare replacement differential
    If installing a replacement differential, transfer any necessary components from the old unit such as brake backing plates, brackets, or ABS sensors if not already installed. Clean all mounting surfaces on the leaf spring perches and ensure U-bolt plates are free of debris. Inspect leaf springs for damage or wear while differential is removed.
11. 11

    Install differential assembly
    Position the replacement or serviced differential on the transmission jack and secure with chain or strap. Carefully raise the assembly into position, guiding the axle tubes through the suspension. Align the spring perches with the leaf springs. You may need an assistant to help guide and align the heavy assembly. Raise until spring perches sit properly on leaf springs.
12. 12

    Install U-bolts and initial fasteners
    Install the U-bolt plates and U-bolts on both sides. Thread U-bolt nuts onto the bolts and tighten in a crisscross pattern to draw the axle down evenly onto the spring perches. Torque U-bolt nuts to manufacturer specification (verify exact value in the factory service manual for the 2007 Ram 3500 AAM 11.5 axle). Recheck torque after installing all other components.
13. 13

    Reconnect suspension components
    Reconnect the track bar to the axle bracket if equipped. Reinstall sway bar end links to their axle mounting points. Reinstall shock absorber lower mounts and torque to specification. Ensure all suspension components move freely and are not bound.
14. 14

    Reconnect driveshaft and ABS sensors
    Align the marks made during disassembly and reconnect the rear driveshaft to the pinion flange. Install new U-joint strap bolts if old ones are damaged. Torque U-joint strap or flange bolts to manufacturer specification (verify exact value in service manual — heavy-duty AAM 11.5 axle values are typically higher than light-duty specs). Reconnect ABS wheel speed sensor connectors and secure all wiring with clips and brackets.
15. 15

    Reconnect brake components and fill differential
    Reconnect parking brake cables to calipers or backing plates and reinstall any cable clips. Reinstall any brake line brackets that were removed. Using a fluid pump, fill the differential with the manufacturer-specified gear oil (AAM 11.5 axle typically requires approximately 3.5-4.0 quarts of 75W-140 synthetic gear oil; verify exact capacity and viscosity in the service manual) through the fill plug opening. Fill until oil reaches the bottom of the fill plug hole. Install and torque the fill plug. Reinstall differential cover with new gasket or RTV silicone, torquing bolts in a crisscross pattern.

Reassembly

1. Reinstall rear wheels and torque lug nuts to specification (typically 135 ft-lbs for Ram 3500, verify in service manual)
2. Lower vehicle to ground and perform final torque on lug nuts
3. Recheck all fastener torques, particularly U-bolts and driveshaft bolts
4. Check for any fluid leaks around differential cover and fill plug

Verification

• Start vehicle and verify no abnormal noises from differential
• Test parking brake operation to ensure cables are properly connected
• Test drive vehicle in a safe area, making gentle turns in both directions to verify proper differential operation
• Listen for any grinding, whining, or clunking noises that would indicate improper installation
• After test drive, recheck differential fluid level and top off if necessary
• Inspect under vehicle for any fluid leaks from differential
• Verify ABS warning light is not illuminated, indicating wheel speed sensors are properly connected
• After 50-100 miles, retorque U-bolt nuts as they may settle

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